S. Truett Cathy, the conservative Christian founder of fast-food chain Chick-fil-A, died early Monday at age 93, the company said.

Mr. Cathy, an entrepreneur from an early age, built Chick-fil-A from a small diner founded in an Atlanta suburb 68 years ago into the top fast-food chicken chain in the U.S. Known for its grounding in the tenets of the founder's religious devotion as well as for its fried-chicken sandwiches, the closely...